<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>title</title>
    <style type="text/css">
        .div-inline {
            float: left;
            margin: 5px;
            width: 400px;
            height: 200px;
            border: 5px solid;
        }
        #box4 {
            width: 400px;
            height: 200px;
            border: 5px solid;
            margin-left: 420px;
        }
    </style>
</head>
<body style="text-align: center; line-height: 200px; font-weight: bolder">
<div style="overflow: hidden; width: max-content">
    <div class="div-inline">1</div>
    <div class="div-inline">2</div>
    <div class="div-inline">3</div>
</div>
<div style="overflow: hidden; margin: 5px">
    <div id="box4">4</div>
</div>
</body>
</html>